a tiny fully formed individual that (according to the discredited theory of preformation) is supposed to be present in the sperm cell

Hippocrates and Aristotle proposed the idea of what they called pangenes, which they thought were tiny pieces of body parts. They thought that pangenes came together to make up the homunculus, a tiny pre-formed human that people thought grew into a baby. In the 1600s, the development of the microscope brought the discovery of eggs and sperm. Antonie van Leeuwenhoek, using a primitive microscope, thought he saw the homunculus curled up in a sperm cell. His followers believed that the homunculus was in the sperm, the father “planted his seed,” and the mother just incubated and nourished the homunculus so it grew into a baby. On the other hand, Regnier de Graaf and his followers thought that they saw the homunculus in the egg, and the presence of semen just somehow stimulated its growth. In the 1800s, a very novel, “radical” idea arose: both parents contribute to the new baby, but people (even Darwin, as he proposed his theory) still believed that these contributions were in the form of pangenes.

A homunculus is a failed attempt to revive a dead person using the art of alchemy in the anime Full Metal Alchemist. (This practice is often referred to as human transmutation, and is forbidden.) There is some ambiguity whether or not a homunculus is truly a reincarnation of that person. A homunculus is not a human and supposedly has no soul. However, Lust and other homunculi are able to recall events from their past life.

Homunculi are nearly indestructible and do not age. In addition, each one has a special, deadly power. For example, Lust can extend her nails to use as a deadly weapon and Sloth can transform from a solid state to that of a liquid. Homunculi become paralyzed when in close proximity to parts of their former bodies. The resulting paralysis or loss of consciousness often aids in one of the few ways to kill a homunculus: sealing via an alchemical array. This causes the homunculus to expel the red stones which fuel them, and results in the body of the homunculus dissolving and/or weakening. Most homunculi are incapable of using alchemy, but there are exceptions.

The main villains of the anime series of Fullmetal Alchemist. An artificial human being that has a philosopher stone has its heart. Their are 7 of them and each are based on one of the seven deadly sins and have their own unique powers. They are near immortal and have fast regeneration. They are created by Father the original homunculus and serve him due to their thankfulness that he created them, all except Greed. They all hold negative views on humans as being an inferior species to them again except Greed. The only way to kill one is to kill them over and over again until they run out of souls in their philosopher stone.

Lust was the second homunculus by Father and was later continually burned by Mustang untill she finally die. Her powers let her extend her fingertips like a spear. Giving her the nickname the "Ultimate Spear."

"Little man". The mapping of sensory and motor pathways in the brain is called the homunculus, because, when sketched, they make the figure of a man. Also used in philisophy to talk about who is controlling the mind.